Method for manufacturing a plate shaped product and plate shaped product manufactured thereby

ABSTRACT

A method is presented for manufacturing a plate shaped product, comprising the steps of manufacturing a first intermediate product which comprises at least, successively, a carrier, a plastic printing layer, a decorative print layer and a plastic protective layer, by using a multiple coating process, manufacturing a second intermediate product which comprises at least one plastic layer, by using at least a calendering process, and combining the first and second intermediate products by laminating, such that the second intermediate product is attached to the first intermediate product. Further a plate shaped product is provided which is manufactured using said method.

CLAIM OF PRIORITY

This patent application is a Continuation Application and claims thebenefit of priority of U.S. Patent Divisional application Ser. No.15/221,917, filed 28 Jul. 2016, which claims the benefit of priority ofU.S. patent application Ser. No. 13/363,874, filed 1 Feb. 2012, issuedas U.S. Pat. No. 9,415,574 on 16 Aug. 2016, which claims the benefit ofpriority of European Patent Application Serial Number 11152888.1, filed1 Feb. 2011, the benefit of priority of each of which is claimed hereby,and which is incorporated by reference herein in their entirety.

TECHNICAL FIELD

The invention firstly relates to a method for manufacturing a plateshaped product, especially a plate shaped product which mainly comprisesplastic materials. The term “plate shaped product” may refer to variousproducts, such as floor products, wall products, ceiling products oralike.

BACKGROUND

To date there exist several methods for manufacturing such a plateshaped product, such as for example a floor product. A first typicalmethod for manufacturing a (mainly plastic) floor product in roll shapeis described in patent application US-A-2004/0102120. According to thisknown method a continuous multiple coating process is carried out toapply several layers on top of each other.

Typically, such layers may comprise a plastic backing layer, a carrier,a plastic printing layer, a decorative print layer and a plasticprotective layer. The roll shaped floor product obtained may beconverted into modular floor products. This known coating methodgenerally produces highly flexible and soft floor products. Such aflexibility is inherent to the coating method which uses plastisols witha low viscosity which is controlled by a number of liquids in theplastisol, such as plasticizers, diluents and additives. During asubsequent gelling process the plastisols gel and the separate layersare interconnected. The plasticizers act as softeners for keeping thefinal floor product flexible.

Patent application US-A-2007/0166516 describes another typical methodfor producing (mainly plastic) modular floor products by calendering andlaminating techniques. According to this known method several continuoussheet or foil shaped layers are produced by calendering, whereafterthese layers are laminated together using a continuous laminatingprocess.

As an alternative for this known continuous laminating a so-called hotpress method may be used which defines a discontinuous laminatingprocess using short slabs cut from the produced sheet or foil shapedlayers.

BRIEF SUMMARY OF THE INVENTION

Both the continuous and discontinuous processes suffer from a number ofdrawbacks. The processes involve high capital cost. To produce theseveral sheet or foil shaped layers (e.g. backing layer, printing layerand wear layer) multiple calender lines are required which each shouldbe provided with a melting unit (e.g. an extruder) and a dry blendmixing unit, adding to the cost. Further a separate printing line willbe needed. Finally an intermediate storage for the sheet or foil shapedlayers on a roll should be provided for.

Using this known method floor products are obtained which generally areharder and stiffer than the floor products obtained by the coatingmethod. However, the most calendered and laminated floor products thusobtained have a poor dimensional stability and often show shrinkagephenomena and a rest stability which sometimes call for additionalannealing steps (however without fully preventing any residualshrinkage).

In view of the above it is an object of the present invention to providean improved method for manufacturing a plate shaped product.

In accordance with the present invention such a method is characterizedby the steps of:

-   -   manufacturing a first intermediate product which comprises at        least, successively, a carrier, a plastic printing layer, a        decorative print layer and a plastic protective layer, by using        a multiple coating process,    -   manufacturing a second intermediate product which comprises at        least one plastic layer, by using at least a calendering        process,    -   combining the first and second intermediate products by        laminating, such that the second intermediate product is        attached to the first intermediate product.

The method according to the present invention combines the advantages ofthe coating process at one hand and the calendering process at the otherhand. Thus, the product obtained by the method will not or only in alimited sense show the disadvantages of the products obtained by theabove-mentioned known methods. The first intermediate product offers thefinal plate shaped product an excellent dimensional stability due to thepresence of the carrier, whereas the second intermediate product makesthe final product sufficiently stiff to present it in a modular shape,if required.

In an embodiment of the method according to the present invention thefirst intermediate product is manufactured with a plastic backing layerat the side of the carrier opposite the plastic printing layer and thesecond intermediate product is attached to said backing layer.

In a preferred embodiment of the method according to the presentinvention at least one of the protective layer and backing layer, ifprovided, of the first intermediate product are provided with a surfacestructure produced by mechanically embossing. Such a mechanicalembossing is an alternative for chemical embossing (such as for examplea standard foaming process for the printing layer) and is often used forstructures out of register with the print. Chemical embossing is appliedin register with the print, but generally will yield a more shallow andless accurate structure. In most cases only the protective layer will beembossed mechanically.

In an embodiment, then, both the protective layer and backing layer ofthe first intermediate product are provided with a surface structureproduced by mechanically embossing.

However, as an alternative it is possible too that both the protectivelayer and backing layer of the first intermediate product are providedwith a surface structure entirely produced by gelling.

In accordance with yet another preferred embodiment of the methodaccording to the present invention, for manufacturing the protectivelayer of the first intermediate product a thermic cross-linking processis used during a gelling process. As a result, a very hard protectivewear layer (e.g. comprising PVC) may be obtained. This may be animportant requirement for, for example, a floor product (e.g. a floortile). According to such a thermic cross-linking part of theplasticizers normally present in the wear layer may for example besubstituted by reactive methacrylates (or other reactive components) andan intiator. Latter will be activated at high temperature and initiatesa cross linking. Apart from the gelling process during which theplasticizers diffuse into the plastic (PVC) grains and cause the wearlayer to harden, an additional cross linking between the methacrylatesamong themselves and between the methacrylates and the PVC chainsoccurs. This results in a wear layer (protective layer) which is veryhard.

As an alternative, however, it is possible too that for manufacturingthe protective layer of the first intermediate product a foil islaminated on top of the decorative print layer.

According to another embodiment of the present method the carrier of thefirst intermediate product is impregnated with a plastic material, e.g.PVC, before being attached to an adjoining layer by said coatingprocess. Such an impregnating step may improve the efficiency of themethod. The impregnation layer will define a basis for the subsequent(plastic or plastisol) layers.

In such a case, as a further improvement of said method, the carrier,after being impregnated, may be heated for pre-gelling the plasticmaterial.

When, in accordance with yet another embodiment, the method according tothe present invention comprises the further step of providing aprotective lacquer layer on top of the protective layer, the life spanof the protective layer (and thus of the plate shaped product) may beprolonged.

In a further embodiment of the method the step of manufacturing a secondintermediate product further comprises the step of laminating togetherlayers. This encompasses both the possibilities of creating a layer bylaminating sub layers or creating an assembly of layers for obtainingthe second intermediate product.

According to another embodiment of the present invention the step ofmanufacturing a second intermediate product comprises providing acarrier and two calendered backing layers laminated at opposite sides ofsaid carrier. As a result a final plate shaped product will be obtainedcomprising two carriers: a first one in the first intermediate productand a second one in the second intermediate product, which togetheroffer the final plate shaped product an excellent dimensional stability(for example the flatness of the product can be increased and shrinkreduced).

The backing layers laminated at opposite sides of said carrier may havea different composition and/or thickness, but it is possible too thatthe backing layers laminated at opposite sides of said carrier have asimilar composition and/or thickness. Each backing layer further maycomprise a single layer or a composite layer.

In another embodiment of the method the step of manufacturing a secondintermediate product comprises providing at least one, and preferablytwo or more foils, possibly without carrier. Such an embodiment may beuseful especially when a very thick final plate shaped product, such asa floor product is required.

The final plate shaped product obtained thus may come in differentshapes. For example, the method may further comprise the step of cuttingthe product to size after the step of combining the first and secondintermediate products, for example for obtaining products like tile orplank shaped floor products.

The method according to the present invention further may comprise thestep of providing the plate shaped product with edge groove and/orconnector provisions. Connector provisions may be needed, for example,for interconnecting adjacent floor products and may comprise snapprovisions as is known per se.

Without pretending to be complete, the following embodiments may bementioned too: as carrier in the first intermediate product a non wovenglass fiber carrier may be used, whereas as carrier in the secondintermediate product a woven or non woven carrier may be used which maybe based on glass fiber material; a step may be used of providing asurface structure in the protective layer and/or backing layer of thefirst intermediate product and/or the side of the second intermediateproduct facing away from the first intermediate product, wherein such astep of providing a surface structure may be carried out by chemicalembossing (i.e. providing an embossed pattern by a localized expansionof a layer of foam); a step may be used of providing a slip resistantcoating or an adhesive coating covered with a release foil on the sideof the second intermediate product facing away from the firstintermediate product.

In a second aspect the present invention relates to a plate shapedproduct comprising, on top of each other, a first intermediate productwhich comprises at least, successively, a carrier, a plastic printinglayer, a decorative print layer and a plastic protective layer eachcoated one on top of the other, and a second intermediate productattached to said first intermediate product and comprising at least onecalendered plastic layer, which plate shaped product is manufacturedusing the method according to the present invention.

In one embodiment of the plate shaped product it further comprises aplastic backing layer at the side of the carrier opposite the plasticprinting layer. Further it is possible that the second intermediateproduct comprises at least one, and preferably two or more foils,possibly without carrier.

In another embodiment of said plate shaped product the secondintermediate product comprises a carrier and two backing layerslaminated at opposite sides of said carrier. The carrier in the firstintermediate product may be a non woven glass fiber carrier, whereas thecarrier in the second intermediate product may be a woven or non wovencarrier which may be based on glass fiber material, and of which theposition is selected such that the dimensional stability (such asflatness) is augmented in an optimal manner.

Further it is possible that a slip resistant coating or an adhesivecoating covered with a release foil is provided on the side of thesecond intermediate product facing away from the first intermediateproduct.

The plate shaped product according to the present invention may have theshape of a floor tile or floor plank or may be provided in a roll form.

BRIEF DESCRIPTION OF THE DRAWING

Hereinafter the invention will be elucidated while referring to thedrawing.

FIG. 1 shows a schematic cross section of an embodiment of a plateshaped product embodied as a floor product in accordance with thepresent invention.

DETAILED DESCRIPTION

Referring to the drawing, an embodiment of a floor product in accordancewith the present invention is illustrated in a schematic cross section(it is noted that this cross section is not necessarily to scale andthat the relative dimensions of its constitutive parts may differ fromwhat has been illustrated). This floor product comprises a first upperintermediate product 1 and a lower second intermediate product 2manufactured separately and thereafter joined together in manners to bedescribed hereafter.

In the illustrated embodiment the first upper intermediate product 1comprises, successively, a PVC plastisol backing layer 3, a non-wovenglass fiber carrier 4, a PVC plastisol printing layer 5, a decorativeprint layer 6 and a PVC plastisol protective layer 7. These layers arepositioned one on top of the other using a multiple coating process.Each layer has its specific composition, thickness, weight and functionin the final floor product. The most important constituents of theplastisols are PVC, fillers, plasticizers, viscosity controllers,stabilisers and foaming means.

A first step for manufacturing the first intermediate product 1 maycomprise impregnating a glass fiber carrier 4 with a first PVC paste.Next the impregnated carrier is transported over a heated roller forpre-gelling (harden) the liquid paste. As a next step the printing layer5 is coated on top of the impregnated carrier 4. The printing layer 5,which will define the basis for the decorative print layer 6, maycomprise a white foam layer.

On top of the printing layer 5 the decorative print layer 6 is provided,e.g. by an appropriate printing technique (such as rotative engravedprinting). The used inks may comprise an inhibitor inhibiting thefoaming of the printing layer 5 for locally creating a relief (such as aseam in a tile shaped floor product). Finally the protective layer 7will be coated on top of the decorative print layer 6. Mostly theprotective layer 7 will be a transparent PVC layer which offers thefloor product important mechanical properties.

Preferably, for manufacturing the protective layer 7 of the firstintermediate product 1 a thermic cross-linking process is used during agelling process. As a result, a very hard protective wear layer may beobtained. This may be an important requirement for a floor product (e.g.a floor tile). According to such a thermic cross-linking part of theplasticizers normally present in the wear layer are substituted byreactive methacrylates and an intiator. Latter will be activated at hightemperature and initiates a cross linking. Apart from the gellingprocess during which the plasticizers diffuse into the plastic (PVC)grains and cause the wear layer to harden, an additional cross linkingbetween the methacrylates among themselves and between the methacrylatesand the PVC chains occurs. This results in a wear layer (protectivelayer) which is very hard.

Additionally, decorative particles may be dispersed into the protectivelayer 7.

It is possible to pre-gel the PVC plastisols in the printing layer 5 andprotective layer 7 by a heated roller. Also, the carrier 4 may bepre-gelled.

Next the backing layer 3 may be coated to the impregnated carrier 4, forexample using a foaming technique (e.g. chemically or mechanically, asis known per se). This backing layer 3 offers the final floor productthe required comfort (resilience and damping).

Next the intermediate product 1 is placed in a hot air furnace (heatedto for example 205° C.) for a few minutes and a complete gelling andfoaming will occur. After cooling the floor product a laquer layer (notillustrated) may be applied on top of the protective layer 7. As analternative the laquer layer is applied previously to gelling.

Finally, the protective layer 7 and the backing layer 3 may be providedwith a surface structure (for example by mechanically embossing).

The obtained first intermediate product 1 may be finished (among othersby cutting it to size, removing edges) and may be stored until laterlaminating with the second intermediate product 2.

The second intermediate product 2 is not manufactured by coatingtechniques but by calendaring (and possibly laminating) processes using,among others, calendering (and laminating) rolls. In an exemplaryembodiment of such calendaring processes firstly compounds based on PVC,mineral or organic fillers, plasticizers, additives and colorants areproduced which are fed to an extruder. In the extruder a homogenisationand melting of the compound occurs. The extruded material is fed to thecalendering rolls for producing PVC foils.

In the illustrated embodiment the second intermediate product 2comprises a first compact calendered backing layer 8, a carrier 9 (whichmay be pre-coated, e.g. with a plastisol, for enhancing the adhesionwith the calandered layers) and a second compact calendered backinglayer 10. Each of the backings 8 and 10 may comprise several separatelycalendered layers (foils, but also foam layers), if required (forexample for achieving a required minimal thickness) laminated together.The carrier 9 may comprise a woven or non-woven carrier which may bebased on glass fiber material.

The carrier 9 is fed to one or more laminating rolls, together with thebacking layers 8 and 10 and the layers are laminated for obtaining thesecond intermediate product 2. It is possible to pre-heat the backinglayers and/or carrier to improve the lamination, e.g. using infraredlights or heated rolls.

Once the first and second intermediate products 1 and 2 have beenmanufactured, these products are joined by a further lamination processfor obtaining the final floor product. If necessary, finishing steps maybe carried out (among which embossing the upper and lower side of thefinal product, cutting the product to size and the provision ofconnector provisions).

The invention is not limited to the embodiments described before whichmay be varied widely within the scope of the invention as defined by theappending claims.

What is claimed is:
 1. A method of manufacturing a plate shaped floorproduct, comprising: producing a carrier by producing a compound basedat least on PVC, mineral fillers and colorants, feeding said compound toan extruder to obtain an extruded material, and feeding said extrudedmaterial to calendering rolls immediately after extruding the extrudedmaterial; and then providing at least a decorative print layer and aplastic protective layer; and then joining said decorative print layerand said plastic protective layer to said carrier; embossing saidplastic protective layer to form said floor product; cutting to sizesaid floor product; and providing at least one of edge groove orconnector provisions to said floor product for interconnecting adjacentfloor products.
 2. The method of claim 1, wherein said plate shapedfloor product comprises plastic materials.
 3. The method of claim 1,wherein said decorative print layer and said plastic protective layerare provided by using a multiple coating process.
 4. The method of claim1, further comprising providing a plastic printing layer, saiddecorative print layer being provided on said plastic printing layer. 5.The method of claim 1, wherein said joining includes attaching saiddecorative print layer and said plastic protective layer to said carrierby lamination.
 6. The method of claim 1, wherein said carrier is stifferthan said decorative print layer and said plastic protective layer. 7.The method of claim 1, wherein embossing comprises chemically embossingsaid plastic protective layer.
 8. The method of claim 1, wherein saidembossing comprises mechanically embossing said plastic protectivelayer.
 9. The method of claim 1, wherein providing said plasticprotective layer comprises laminating a foil on top of the decorativeprint layer.
 10. The method of claim 1, further comprising providing aprotective lacquer layer on top of the plastic protective layer.